1. Click Settings

2. In the Settings pane, click Identities, and then click the account for which you to create a signature.

4. If you primarily send formatted (HTML) messages, you can enable the HTML signature option which allows you to add formatting of your signature; when HTML signature is selected, the Signature text box displays a formatting toolbar.

5. Click Save.

6. In the Settings pane, click Preferences and then click Composing Messages.

7. In the Signature Options section, from the Automatically add signature drop-down list, choose the option to specify the way you want to display your signature:

never—Do not display the signature.

always—Display the signature on all messages, including new messages, replies, and forwards.

new message only—Display the signature on new messages, but no on replies or forwards.

replies and forwards only— Display the signature on replies and forwards but not on new messages.